584 EXPERIMENT STATION RECORD. [Vol.41 



Test tractive efficiency of concrete roads, E. N. Hixes {Concrete [Detroit, 

 Mich.], 14 {191C), No. 2, pp. 56, 57). — Tests in five counties in Michigan are re- 

 ported in whicli a 2-ton truck loaded to capacity was driven over 23S.2.") miles 

 of concrete, gravel, and dirt roads. The average speed in miles per hour was 

 16.4 for concrete roads, 9.5 for gravel roads, and 4.6 for dirt roads. 



A 10-mile test of a 2-ton truck on a concrete road and on an ordinary country 

 dirt, gravel, and sand road to determine relative gasoline consumptions showed 

 that 1.25 gal. of gas and 42 minutes of time were required on the concrete, as 

 against 2 gal. and 1 gill of gas and 1 hour and 24 minutes of time on the 

 country road. 



Concrete construction for rural communities, R. A. Seaton (Nav York: 

 McGrau-Hill Book Co., Inc., 1918, 2. cd., pp. XI +223, pi. 1, figs. S5).— This is 

 the second edition of this book (E. S. R., 36, p. 188), in which the specifications 

 for Portland cement have been revised. 



Absorption tests of slag, stone, and gravel concrete, O. R. Smith {Concrete 

 [Detroit, Mich.'], 14 {1919), No. 4, PP- IH)- — Comparative absorption tests of 

 slag, stone, and gravel concrete shovced that as far as absorption alone is con- 

 cerned there was very little difference between the three types. 



Determination of stresses in wire rope as applied to modern engineering 

 problems, J. F. Howe {Jour. Atner. Soc. Mech. Engin., 40 {1918), No. 12, pp. 

 1016-1021, figs. 8). — This is a mathematical analysis of the stresses in wire 

 rope, from which formulas for the strengtli of strands and the whole rope in 

 static and moving tension, on inclines, under indirect or induced stresses and 

 reverse bending, and suspended horizontally supporting a load are derived. It 

 is the opinion of the autlior that specifications for wire rope should include a 

 tension test, and possibly a bending and torsion test, but that an elongation 

 test is unfair and iintrue to actual conditions. 



Concentrated load tests of yellow pine beams for shear, L. R. Manville 

 and C. R. Hill {Engin. Neivs-Rec., 83 {1919), No. 2, pp. 69-71, figs. 4).— Tests of 

 long-leaf yellow pine beams are briefly reported, from which it is concluded 

 that, with a concentrated load placed a distance from the end support of a beam 

 equal to the depth of the beam, the beam will bold as much as the timber will 

 stand in cross-grain bearing over the supports, and no horizontal shear failure 

 may be expected. 



It is recommended that for the strength of beams in horizontal .shear values 

 roughly 50 per cent greater than ordinary design unit stresses may be used, if 

 the unit shear is computed by the usual method, and if heavy concentrated loads 

 occur near the point of support or within about Ij times the depth of the beam. 

 " Design unit stresses in horizontal shear such as 120-lb. per square inch for 

 long-leaf yellow pine appear to be very conservative for application to maximum 

 end shear under concentrated loads, although no doubt -within safe design limits 

 with a load three depths of the beam from the support. This stress could be 

 increased as recommended above for applied loads nearer the reaction. Timber 

 inspected and graded under the rules proposed by the U. S. Forest Service, 

 dated 1915, which would largely eliminate critical defects, may be used with 

 higher unit stresses, especially in horizontal shear in which defects such as 

 checks and shakes so often play an important part." 



Prolonging life of farm timbers, J. B. Berry {Ga. State Col. Agr. Circ. 66 

 (1917), pp. 8, figs. 6). — This bulletin deals briefly with the creosoting of farm 

 timbers for their preservation. Posts, to be treated, must be peeled, removing 

 the inner bark especially, and thoroughly seasoned. The temperature of the oil 

 must be controlled within the limits of from 200 to 220° F., and should never 

 exceed tlie latter. A deep penetration of the oil should be secured on the part 

 of the post to go into the ground and lor a foot above the ground. 



